TY - CONF A1 - Meng, Xiangmeng A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - A theoretical study of influence of electromagnetic stirring on transport phenomena in wire feed laser beam welding N2 - The additional element from the filler wire in the laser beam welding is usually distributed inhomogeneously in the final weld due to the high solidification rate of weld pool. It has been found that the electromagnetic stirring produced by an external oscillating magnetic field can enhance the material mixing in the weld pool to achieve a more uniform element distribution. However, the magnetic field has a highly non-linear and multi-coupled interaction with the weld pool behavior, which makes the quantitative explanation of the physical mechanism difficult. In this study, the effect of electromagnetic stirring on the transport phenomena in the wire feed laser beam welding is investigated by a numerical modelling. A 3D transient multi-physical model considering the magnetohydrodynamics, heat transfer, fluid flow, keyhole dynamics and element transport is developed. The multiple reflections and the Fresnel absorption of the laser on the keyhole wall are calculated using the ray tracing method. The numerical results show that a Lorentz force produced by the oscillating magnetic field and its induced eddy current gives significant influence on the transport phenomena in the molten pool. The forward and downward flow is enhanced by the electromagnetic stirring, which homogenizes the distribution of the additional elements from a nickel-based filler wire in a steel weld pool. The numerical results show a good agreement with the high-speed images of the molten pool, the fusion line from the optical micrograph and the element distribution from the energy dispersive X-ray spectroscopy. This work provides a physical base for the electromagnetic-controlled laser beam welding and some guidance for the selection of electromagnetic parameters. T2 - ICALEO 2019 CY - Orlando, US DA - 07.10.2019 KW - Magnetohydrodynamics KW - Molten pool dynamics KW - Element transport KW - Laser beam welding PY - 2019 AN - OPUS4-49300 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weltschev, Margit T1 - Compatibility of polymeric sealing materials with biodiesel heating oil blends at different temperatures N2 - Biodiesel is subject to degradation processes like oil and grease. The oxidative degradation products of vegetable oil esters in biodiesel particularly lead to enhanced sedimentation in blended fuels. The polarity of biodiesel increases its solvency and facilitates permeation and extraction. Solvation, swelling and/or extraction lead to changes in the physical properties and chemical changes of polymeric materials. It also accelerates the degradation (hydrolysis and oxidation) of these materials with the loss of additives and stabilizers. The objective of this research was to determine the resistance of frequently used polymeric materials such as ACM, EPDM, FKM, FVMQ, CR, CSM, IIR, HNBR, NBR, PA, PE; POM, PUR, PVC and VMQ in biodiesel and heating oil with 10 %/20 % biodiesel (B10/B20) at 40°C and 70°C. Mass, tensile strength and breaking elongation of the test specimens were determined before and after the exposure for 84 days in the biodiesel heating oil blends. The visual examination of some elastomer test specimens clearly showed the great volume increase until break or partial dissolution. Shore hardness A and D were determined before and after exposure of the test specimens in the biofuels for 42 days. The elastomers CR, CSM, EPDM, IIR, NBR and VMQ were generally not resistant to biodiesel and B10 at 40°C and 70°C. FKM, ACM, HNBR, PA, PE, POM, and PVC showed high compatibility in B10/B20 at 40°C. A lower compatibility was determined for ACM in biodiesel. ACM and HNBR were not resistant in B20 at 70°C. T2 - Biofuels & Bioenergy CY - Rome, Italy DA - 14.10.2019 KW - Heating oil-Biodiesel-Blend KW - Compatibility evaluations KW - Tensile properties KW - Shore hardness PY - 2019 AN - OPUS4-49306 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Busch, R. T1 - Characterization of early crystallization stages in surface-crystallized diopside glass-ceramics N2 - Structure formation in glass-ceramics by means of surface crystallization is a challenging open question and remains elusive to definite answers. In several glass-ceramic systems, oriented crystal layers have been observed at the immediate surface, including diopside and some fresnoite systems. However, it is still open to debate, whether oriented surface crystallization is the result of oriented nucleation or growth selection effects. In the same vein, there is still discussion whether surface nucleation is governed by surface chemistry effects or by defects serving as active nucleation sites. In order to help answer these questions, annealing experiments at 850°C have been performed on a MgO·CaO·2SiO2 glass, leading to the crystallization of diopside at the surface. Different annealing durations and surface treatment protocols (i.a. lapping with diamond slurries between 16 µm and 1 µm grain size) have been applied. Particular focus has been put on earliest crystallization stages, with crystal sizes down to about 200 nm. The resultant microstructure has been analyzed by electron backscatter diffraction (EBSD) and two different kinds of textures have been observed, with the a- or b-axis being perpendicular to the sample surface and the c-axis lying in the sample plane. Even at shortest annealing durations, a clear texture was present in the samples. Additionally, selected samples have been investigated with energy-dispersive x-ray spectroscopy in the scanning transmission electron microscope (STEM-EDX). The diopside crystals have been found to exhibit distinguished submicron structure variations and the glass around the crystals was shown to be depleted of Mg. T2 - 93rd Annual Meeting of the German Society of Glass Technology in Conjunction with the Annual Meeting of French Union for Science and Glass Technology (USTV) CY - Nuremberg, Germany DA - 13.05.2019 KW - Glass KW - Crystallization KW - Diopside KW - EBSD KW - Orientation PY - 2019 AN - OPUS4-49296 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fleck, M. T1 - Surface crystallization of BT0.75S (fresnoite) glass in different atmosphere N2 - Fresnoite glass with excess SiO2 exhibits oriented surface crystallization, in contrast to the stoichiometric glass composition. Recent EBSD studies documented that the crystals in BTS (2BaO-TiO2-xSiO2, x=0-3) can occur in a distinct [101]-orientation perpendicular to the surface and claimed that this orientation is not a result of growth selection. During these previous studies, however, the effect of surface preparation and surrounding atmosphere during the crystallization experiments were not considered. As these parameters may influence crystal orientation, we studied the surface crystallization of a BTS glass (2BaO-TiO2–2.75SiO2) under controlled conditions with the help of light, electron and polarisation microscopy as well as EBSD. Heat treatments for one hour at 840°C of fractured BTS glass surfaces in air resulted in a large number of not-separable surface crystals. This large number of crystals can be caused by dust particles, which act as nucleation agents. As crystal growth velocity could further be influenced by humidity, our experiments are performed in a filtered and dried air atmosphere. The crystal morphology and orientation will be analysed in dependence of the sample preparation and a differing surrounding atmosphere. T2 - 93rd Annual Meeting of the German Society of Glass Technology in Conjunction with the Annual Meeting of French Union for Science and Glass Technology (USTV) CY - Nuremberg, Germany DA - 13.05.2019 KW - BTS KW - Fresnoit KW - Glass ceramic KW - Glass-ceramic KW - Glass PY - 2019 AN - OPUS4-49294 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Beck, Joana T1 - Rezension: Prozessmanagement - Kundennutzen, Produktivität, Agilität N2 - Effizienz und Qualität sind schon immer Antriebsmotoren für die Wirtschaft. Um das heutzutage in einer stetig schneller agierenden Welt zu erreichen, wird konsequentes Prozessmanagement immer wichtiger. Dabei werden Prozesse nicht nur klar und eindeutig beschrieben, sondern auch Kompetenzen, Aufgaben und Verantwortlichkeiten festgelegt, um das Resultat für den Kunden in den Fokus zu rücken und zeitraubende Hierarchiekämpfe zu vermeiden. Der Autor untermalt die gut strukturierten Textpassagen, in denen wichtige Schlagworte fett abgedruckt sind, mit vielen Schaubildern zu Prozessen und übersichtlichen Tabellen. Er gibt dem Leser Werkzeuge in Form von Checklisten sowie Diagnoseplänen und Analyseformularen. Gleichzeitig wird durch beispielhaft ausgefüllte Formulare (Checklisten) der Praxisbezug anhand unterschiedlicher Branchenbereiche wie z.B. Controlling, Produktion, Medizin, etc. hergestellt. Somit liegt hier ein Arbeitsbuch vor für jeden, der gleich losstarten möchte. KW - Prozessmanagement KW - Qualitätsmanagement PY - 2019 DO - https://doi.org/10.1002/maco.201970106 SN - 1521-4176 SN - 0947-5117 VL - 70 IS - 10 SP - 3 EP - 4 PB - Wiley‐VCH CY - Weinheim AN - OPUS4-49303 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Erning, Johann Wilhelm T1 - Observations of copper pitting corrosion in german tap waters N2 - In recent years, a new type of pitting corrosion is observed on half-had copper pipes. examples are given and possible reasons are discussed T2 - Eurocorr 2019 CY - Sevilla, Spain DA - 09.09.2019 KW - Water KW - Pitting KW - Corrosion KW - Copper KW - Drinking PY - 2019 AN - OPUS4-49281 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Erning, Johann Wilhelm T1 - A new type of copper pitting corrosion in german tap waters N2 - Half-hard copper pipes show pitting corosion under conditions until now seen as uncritical. Examples are discussed, possible causes described. T2 - MTECH 2019 CY - Porec, Croatia DA - 09.10.2019 KW - Drinking KW - Pitting KW - Corrosion KW - Copper KW - Water PY - 2019 AN - OPUS4-49283 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Asadujjaman, Asad A1 - Ahmadi, Vahid A1 - Franc, Antoine Michel Claude A1 - Bertin, Annabelle T1 - 2,6-Diaminopyridine and Acrylamide-Based Copolymers with Upper Critical Solution Temperature-type Behavior in Aqueous Solution N2 - A novel cop olyme r based on supramolecular motif2,6-diaminopyridin e and water-soluble acrylamide, poly[N-(6-ace tamidopyridin-2-yl) acrylamide-co-acrylamide], was synthe-size d via rev ersible addi tion–fragmentation chain transfer (RAFT)polymerization with various monomer compositions. The thermo-respon sive behavior of the copolymers was studied by turbidime-try and dynamic light scattering (DLS). The obtained copolymersshowed an upper critical solution temperature (UCST)-typ e phasetransition behavior in water and electrolyte solution. The phasetransition temperature was found to increase with decreasingam ount of acrylamide in the copolymer and increasing concentra-tion of the solution. Furth ermore, the phase transition temperatureva ried in aqueous solutions of electrolytes according to the naturean d concentration of the electrolyte in accordance with theHoffmeister series. A dramatic solvent isotope effect on thetransition temperature was o bserved in this study, as the transitiontemperature was almost 10–12C higher in D2OthaninH2Oatthesame concentration and acrylamide co mposition. The size of theaggregates below the transition temperature was larger in D2Ocompared to that in H2O that can be explained by deuterium iso-tope effect. The thermoresponsive behavior of the copolymers wasalso investigated in different cell medium and found to be exhibitedUCST-type phase transition behavior in different cell medium.Such behavior of the copo lyme rs can be useful in many a pplica-tions including biomedical, microfluidics, optical materials, and indrug delivery. KW - 2,6-diaminopyridine KW - Acrylamide KW - Stimuli-responsive polymers KW - Thermo-responsive polymers KW - UCST polymers PY - 2019 DO - https://doi.org/10.1002/pola.29474 SN - 0887-624X VL - 57 IS - 19 SP - 2064 EP - 2073 PB - Wiley AN - OPUS4-49297 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Artinov, Antoni A1 - Karkhin, V. A1 - Bakir, Nasim A1 - Meng, Xiangmeng A1 - Bachmann, Marcel A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Lamé curves approximation for the assessment of the 3-D temperature distribution in keyhole mode welding processes N2 - A novel approach for the reconstruction of an equivalent volumetric heat source from a known weld pool shape is proposed. It is based on previously obtained weld pool geometries from a steady-state thermo-fluid dynamics simulation. Hereby the weld pool dimensions are obtained under consideration of the most crucial physical phenomena, such as phase transformations, thermo-capillary convection, natural convection and temperature-dependent material properties. The algorithm provides a time and calibration efficient way for the reproduction of the weld pool shape by local Lamé curves. By adjusting their parameters, the identification of the finite elements located within the weld pool is enabled. The heat input due to the equivalent heat source is assured by replacing the detected nodes’ temperature by the melting temperature. The model offers variable parameters making it flexible and adaptable for a wide range of workpiece thicknesses and materials and allows for the investigation of transient thermal effects, e.g. the cooling stage of the workpiece. The calculation times remain acceptably short especially when compared to a fully coupled process simulation. The computational results are in good agreement with performed complete-penetration laser beam welding experiments. T2 - ICALEO 2019 - 38th International congress on applications of lasers & electro-optics CY - Orlando, FL, USA DA - 07.10.2019 KW - Weld pool shape approximation KW - Keyhole mode laser beam welding KW - Numerical simulation KW - Superelliptic Lamé curves PY - 2019 UR - http://icaleo.conferencespot.org/2019-proceedings?qr=1 SN - 978-1-940168-1-42 SP - Paper # Macro 1002 AN - OPUS4-49310 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Barthel, Maria A1 - Rübner, Katrin A1 - Kühne, Hans-Carsten T1 - Aktivierung von Papierasche zur Nutzung als Bindemittelkomponente N2 - In Deutschland fallen jährlich 20 Millionen Tonnen Altpapier an. 75 % davon werden dem Recyclingprozess zugeführt. Dabei bleiben Prozessrückstände wie Deinkingschlämme, Sortierrückstände und Faserreststoffe übrig. Zusammengefasst als Papierschlamm verwerten die Recycler diesen Reststoff thermisch in dezentralen Heizkraftwerken. Die dabei anfallende Papierasche hat mit den Anteilen der Hauptoxide von 59 M.-% CaO, 22 M.-% SiO2 und 13 M.-% Al2O3 eine ähnliche chemische Zusammensetzung wie Portlandzement, wobei sich die Mineralphasen unterscheiden. Durch eine Aktivierung der Papierasche können jedoch hydraulisch aktive Phasen wie Mayenit (C7A12) und Belit (C2S) erzeugt werden. Die Mineralphase Mayenit reagiert schnell mit Wasser zu Calciumaluminathydraten, wodurch der Bindemittelleim schnell ansteift. Die festigkeitsbildenden Calciumsilicathydrate (CSH) in Bindemittelleimen entstehen bei einer späteren Reaktion von Belit mit Wasser. Zur Aktivierung dient eine hydrothermale Calcinierung. Dabei wird Papierasche mit einer Aktivatorlösung (Wasser oder KOH) gemischt und bei 200 °C hydrothermal behandelt, wobei sich Hydratphasen ausbilden. Diese Zwischenprodukte dehydratisieren durch eine anschließende Calcinierung zu reaktiven Calciumsilicaten und Calciumaluminaten. Wie sich die Parameter des Aktivierungsprozesses auf die Mineralphasen auswirken, war Fokus der Untersuchungen. Mit thermogravimetrischen Analysen der Zwischenprodukte konnten die Reaktionsprodukte nach dem hydrothermalen Prozessschritt bestimmt werden. Den größten Einfluss auf den Mineralphasenbestand hat hierbei die Alkalität der Aktivatorlösung. Im zweiten Prozessschritt, der Calcinierung, ist die Temperatur der wesentliche Faktor für die Ausbildung reaktiver Phasen. Die Ergebnisse kalorimetrischer Untersuchungen an Leimen aus den calcinierten Proben dienten der Auswahl der optimalen Calcinierungstemperatur. Die gesamte Reaktionswärme war für die Proben, welche bei einer Calcinierungstemperatur zwischen 700-800 °C hergestellt wurden, am höchsten. T2 - GDCH-Tagung Bauchemie CY - Aachen, Germany DA - 30.09.2019 KW - Papierasche KW - Zement KW - Hydrothermale Calcinierung KW - Bindemittel PY - 2019 SN - 978-3-947197-13-2 VL - 54 SP - 16 EP - 24 CY - Aachen AN - OPUS4-49312 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -